CA2545594A1

CA2545594A1 - A method for manufacturing a solid plating material and the solid plating material manufactured by the method

Info

Publication number: CA2545594A1
Application number: CA002545594A
Authority: CA
Inventors: Wataru Hisada; Kenji Tamaki
Original assignee: Individual
Current assignee: Sintobrator Ltd
Priority date: 2003-11-12
Filing date: 2004-10-22
Publication date: 2005-05-26
Also published as: DE112004002179B4; US20090013904A1; CN1886534A; KR20060123143A; DE112004002179T5; WO2005047567A1; JPWO2005047567A1

Abstract

A process for producing a solid-plated material having a coating layer excellent in conductivity and durability. A coating fluid containing an organic binder is mixed with conductive particles for plating and metal particles for binding to prepare a suspension. The suspension is sprayed on core particles which are being centrifugally fluidized to thereby form on the surface of the core particles a coating layer comprising the plating particles and the binding metal particles tenaciously bonded with the organic binder.
Thereafter, the core particles are heated to a temperature not lower than the melting point of the binding metal particles to thereby remove the organic binder by pyrolysis and simultaneously melt the binding metal particles. Thus, a fusion-bonded layer containing the plating particles tenaciously bonded can be formed on the surface of the core particles. When particles of a material having excellent conductivity are used as the particles for plating, a solid-plated material having a coating layer excellent in conductivity and durability can be produced.

Description

17ESCP,IPTION
A Method for Manufacturing a Solid Plating Material and, the solid Plating Material Manufactured by the Method Technical Field [0001]
This invention relates to a method for manufacturing a solid plating material and the solid plating zneterial manufaetured by the method, which is used to form coated ~l,ms on products such as separators of a variety of fuel cells for automobiles, stationary power sources, or mobile power sources, the markets for which products are su~ciently large and growing. Especially, the coated ~l,ms are formed by blasting an,d hs~ra an e~ccellent electrical conductivity.
Background of the Ixi,vention [00021 As a method for forming coated f7lms on the surfaces of products to modify the surfaces, there is plating, such txs electroplating, hot-dip plating, diffusion plating, or vapour-deposition plating, axed Fusion for forming coated films on the surfaces of products by injecting hewed and molten metal powder. These methods for forming the coated films need expensive facilities, because the facilities used for the xn.ethads are large. Further, it is a problem of these methods in that if the materials of the coated films are nonmetal, such as oxidative products, these methods cannot be used for forming the coated films on the surfaces of the products.
[0003]
To solve those problems, the inventors in this application developed a method for blasting tv farm coated fil.zns on the surfaces of products, instead of plating ar fusion. They also developed a solid plating material for the blasting process. These are disclosed in Patent Docmz~.eznts 1, 2, and 3, which were published prior to the ~~ling of this application.
[0004]
Latent Document 1 discloses a solid plating xx~aterial. The solid i plating material is made ~xom a central particle (hereafter "a core particle") coated by plating. The core particle has a diameter of 30- 300 ~ m and a hardness of 400-2000 Hv, and is made from a hard metal alloy, The core particle is plated with a metal powder (hereafter a "plating powder"), such as gold, silver, copper, or nickel, which has an excellent electrical conductivity (lower electrical resistance). Patent Doc;uxnent 1 indicates that there are gold, silver, etc., which are more expensive, as a plating powdex having an excellent electrical conduetiwity [0005]
Patent Document 2 discloses a method for ~orming coated ~l.ms on the surfaces of separators of fuel cells. These coated fiLm.s have an excellent electrical conductivity (lower electrical resistance) and are formed by blasting solid plating materials with a flow of dxy air, impellers, a high pressure flow of water, or a flow of inert gas.
[0006]
Patent Document 3 discloses a method for mar~ufacturing a solid plating material and the solid plating material manufactured by the method.
This solid plating material is manufactured by the following steps: First, coated layers are formed on the surfaces o~ core particles having a diameter of less than 2 mm, and- being made ~zoz~a steel, a non-ferrous metal, a non-ferrous allay, or a nanznetal znatexie.l, by injecting a coating fluid that includes an organic binder. Second, a suspension liquid is prepared by mixing the coating fluid with inorganic powder, as a platixig powder, having a diameter of less than 0.5 mm, and being made fiom zinc, copper (base metaD, gold, silver (precious metal), or an oxidative product (nonmetal). Lastly, the surf~xcas a~ the coated I,~ayaxs o~ the coxe paxticles are plated with the plating powder by ix~jecting the suspension liquid on the surfaces.
Patent Document 1~ Japanese Patent Publication Laid-open No. 2001-U898?0 Patent Document 2= Japanese Patent Gazette No. 3468?39 (U.S. Patent No. 6?6953) Patent Aacument 3: Japanese Patent ~'ubli.catian Laid-open No. 2008-X6088 Disclosure of Invention Z

[00077 The methods ~or manufacturing a solid plating material that are used for blasting ixr order to farmv coated hlzns having improved electrio~l, conductivity, and that are disclosed in Patez~t Documents 1 a,nd 3, have the following problems.
taoos~
Namely, the method disclosed ire Patent Documex~t 1 discloses a plating techz~ology Thus, since it needs large facilities, there is a problem in that the costs of the plant used for the method for manufacturing a $alid plating material ixxcrease.
[0009 Six~ce the method disclosed in Patent Document 8 does not use plating technology, it does not have the same problem as does the method di,gclosed in Patent Document x. However, when coated $lms are ~arxned on the surfaces a~ products by blasting solid plating materials in order to form coated films having excellent electrical conductivity, which solid plating materials are manufactured by the xnethod disclosed in Patent Document 3, it becomes a pra'blezn in that no coated elms having an adequate high electrical conductivity can be formed_ The reason ~or this problem is as follows: Since the coated layer of the solid plating mrxterial includes the plating powder and the organic binder, the coated .films formed an the surfaces of the products also include bath the plating powder and the organic binder. This orga,uic binder is used to increase the bonding strength between the coated $.Ims and the plating powder and to improve the durability of the solid plating materials. However, since the organic binder is a nonconductivmnaterial, the electrical resistance, such as surface resistance ox contact resistance, of the coated layor plated with the solid plating material, increases.
L0010~
As stated zn the above paragraph, whan it is required to form a coated film having excellent electrical conductivity, it is not proper to use the solid plating materials which are manufactured by the method disclosed in Patent Document 3. The contents of the plating powder and the organic binder in the coated layer affect the electrical conductivity and the durability of the solid plating materials (the bonding strength between the coated layer and the plating powder), which durability is requiied 5a that the solid plating materials can be repes,tedly used, 'X'hus, by the z~,etl~zod for manufacturing the solid plating materials disclosed in Patent Document 3, since there is a oozyfl.ict between the electrical conductivity of the coated layer and the durability o~the solid plating materials, it is difficult to manufacture solid plating materials having both excellent electrical conductivity and excellent duxabzl,ity.
[0011]
This inventiox~ solves these problems. Namely, this invention provides a method for manufacturing a solid plating material having both excellent electrical conductivity and excellent durability, and the solid plating materials manufactured by the method.
[00x21 The method for manufacturing a solid plating material of this invention is comprised of:
s, step for preparing a suspension liquid made by mixing a oostlng fluid which includes an or ganio binder, a plating powder having electrical conductivity, and a metal powder to be used for binding, a step for forming coated layers that include the plating powder s.nd the metal powder, and vc~hich are bound to surfaces of corn particles with the organic binder by means of injecting the suspension liquid on the surfaces of the core particles v~rhile the care particles are being agitated by centrifugal fluidization, and a step fox heating the core particles above the melting temperature of the metal powdez to be used for bintlir~g to remove the organic binder and to form deposited layers of the platix~g powder by melting the metal po~rder.
[0013]
Zn the i.nvantion stated in the above paragraph, by means of injecting the suspension liquid onto the surfaces of the core particles while beating the care particles from 30-70 °C, solid plating matezi,als having coated layers which have r.nore excellent electrical conductivity and d.'u~rability can be manufactured.
[0014]
It is preferable to control the flow rate of the suspension liquid to inject it onto the core particles so that it becomes 0.~-2 glmin.
[oo a. s]
~'uzther, it is preferable that the coating ~~uid consist of water or a mixture of water and alcohol which contains 4% by mass of the organic binder.
[001 ~]
It is pze~ez~rxblo that the plating powder consist of powder of an electrical conductive ceraxx~ic having an average tliametex of less than 20 ~. m. Further, it is preferable that the melting temperature of the metal powder to be used for binding be lower than that of the core particles, and that the average diameter of the metal powder to be used far binding be less than 20 ,u na.
(ool~J
It is mare preferable that the average diameter of the core particles be less than 2 mnx. Particles made from a hard metal alloy, steel, nonferrous metal, or a nox~xn.etallic inorganic substance can be used as the core particles.
[0018]
In the process for heating the core particles after forming the coated layers, when the melting temperature of the z~a.etal, powder to be used for binding is greater than or equal to 850 °G, or it is 50 °C or more of the starting temperature of the oxidization of the plating powder, it is preferable that the core particles be heat-trea'ted in a non-oxidative atmosphere. In contrast, when the melting tezz~,perature of the metal powders to be used for binding is less than 350 °~, or it is less than 50 °C below the starting temperature of the oxidization o~ the plating powder, it is prcfErable that the core particles be heat-treated zn air.
(0019]
It is preferable that the solid plating materis,ls be rxa,az~.ufaetured so that the percentage of the plating powder to the care particles becomes less than 5% by mass, and that the percentage of the metal powder to be used far binding the core particles becomes Iess than 3% by zn.ass, [0020]
The solid plating materials of this invention are manufactured by means of the method explained above.
(0021]
The method fez manufacturing the solid platiz~g materials of this invention is comprised of a step for forming the coated layers. These layers include the platix~g po~uu'der and the metal powder. The coated layers are bound to the surfaces of the core particles with the organic binder. It is further comprised of a step far heating the core particles until they are above the melting temperature of tk~e metal powder to be used for binding, as a final heat treatment, to pyrolytically decompose the ozganic binder and to retrieve it. 'Then the deposited layers, which include the platizxg powder, are formed an the surfaces of the core particles by means of melting the metal powder to be used for binding. Consequently, deposited layers having excellent durability can bo formed. If the xz~.ots.l, powder h;~rring electrical conductivity is used as the plating powder, solid plating material which can form z~on-oxygenated coated films having excellent electrical conductivity on the surfaces of the products can be manufactured.
Preferred Embodiments of the Invention ~Q022]
Below, the pzeferred embodiments oftkze iz~vention are explained.
[0023]
Prior to xnanufacturing the solid plating material of this invent~.on, a suspension liquid is prepared by mi~i,ng a coating fluid that includes an organic binder with a plating powder and a metal powder to be used for binding.
[002~k]
Next, coated layers are formed by means of infecting the suspensioz~
liquid on the surfaces of care particles while the care particles are being agitated by centrifugal fluidization and are heated to a predetermined temperature. The coated layezs include the plating powdez and the metal powder, which layers are bound to the surfaces of the core particles s~rith the organic binder. .
Cooz~l Then, after forming the coated layers on the surfaces of the core particles, the core particles are heated to above the melting temperature of the metal powder to be used for binding. Consequently, the organic binder is pyrolytically decomposed and removed fronx the coated layers, and the metal powder to be used for binding is molted. The melted metal powder to be used fox binding can also firmly bind the plati.~xg powder to the coated layers.

(00261 In the method for manufacturing the solid plating material explained abarre, ds the casting ~(uid, water, az a mixture of water and alcohol which includes a vi.x~yX or rxn ~xcz~ylate organic 'bi.x~der, can be used. The concentration, of the oxgaz~i.c binder must be withxz~ a predetermined scope so that the argazric binder can be uniformly injected. Gez~erally, since the viscasi.ty of the organic binder is proportional to the concentration o~ it, it i.s preferable to set the con,cezl,txtxti,on of the organic binder to be less than 4% in order to avoid a nonuniform injection.
(0027]
As the organic binder, PVA (polyvinyl alcohol), modified PVA, PVP
(poly~rinylpyrrolidone), and a methacrylic acid copolymer can be used.
(0028]
As the plating powder, nonoxide ceramics having electrical conductivity, such as TiN, '1'1C, VG, NbC, or MaSi2, can be used. rt is preferable that the average diameter of the plating powder be less than 20 a m.
(0029]
In addition to gold yr ssihrer, copper or tin, which are cheaper than gold and silver, can be used as the metal powder to be used for binding. The melting temperature of tho metal powder to be used for binding must be less than that of the core particles. Further, it is preferable that the average diameter of the metal powder be less than 20 ~ m.
[0030]
The reason that it is preferable that the average diameters of tho plating powder and the metaX powder to be used for binding be less than 20 ,u xn: is as ~ollaws~ Tf the average diameters of the plating powder and the metal. powder to be used far binding are greater than 20 ,u m, it becomes difficult to form the uniform coated layers an the surfaces of the core p articles.
(0031]
Particles of a hard metal alloy, pazticles of steel, such as high speed steel or carbon steel, particles of a nonferrous metal, such as copper, or particles df n nonmetallic inorganic substaz~ce, such as glass beads ar aXuminum oxide, can be used as the care particles. Tt is more pre~ezable that the average diameter of the core particles be less than 2 mm. The reason that it is naoxe pze~erable that the average di,axneter of the core particles be less than 2 zz~m is as ~allaws: If the average diameters of the core particles are greater than 2 zuzu, the surfaces o~ the products which are blasted become rough, and the deforn.~.ati.azxe of the pxaducts axe increased.
[0032]
When the suspension liquid is injected from a nozzle, it is preferable that the core particles be agitated by centrifugal fluidization and heating until a temperature of 30 - 70 °C i.s reached. rf the care particles are heated below 30 °C, it would be hand foz a solvent, such as water, in the coating liquid, to ese~tpe as vapor, and it would take a long time to dry the coated layers. In contrast, if the cone p$rticles are bested to above 70 °C, the solvent would t~uicl~ly escape as vapor however, then, when the coating liquid is injected, a nonuniform 'binding on 'the surfaces of the core particles of the ple.ti,ng powder, the metal powder to be used for binding, axed the organic bindex, which is a substance dissolved in the coating liquid, is caused.
[003 3]
It is preferable that the flog rate of the suspension liquid be controlled so that it is injected onto the surfaces of the cone particles at 0.6-2 glmin. If the flow rate of the suspension liquid is less than 0.~ glmin, it would tale a long timo to inject it. In cazxtrast, i.f i:he flow rate of the suspension liquid xs mare than 2 g/min, a nonuniform bixxdxng of the substance dissolved izr the coating liquid would be caused.
[0034 Tn the final process for heating the core particles after farming the coated layers, when the melting teznpers.ture of the metal powder to be used for binding is 3~0 ~C or xo,ore, or it is 50 '~C or more below the starting temperature of the oxidization of the plating powder, it is preferable that the core particles be heat-ireated in a non-oxidative atmosphere, such as z~.itrogen gas or argon gas. k'ax farming the coated layers having electxiaal coz~.ductivity, if the core particles are heat-treated in an oxidative atmosphere, such as air, since a ceramic having an electrical conductivity, which is used as the plating powder, is oxidized, the electrical resistance of the coated layers bound to the surfaces of the core particles increases. Consequently, a corxtiz~g having a lower electrical conduetxvity may be formed on the surfaces of the products. In contrast, when the melting temperature of the metal powder to be used for binding is less thazA 350 °C, or it is less than 50 °C
below the starting temperature ~ox the vx~idization of the pl;~ting powder, the core particles may be heat-treated in air_ [0031 In the method for manufacturing the solid platzng material statod aborre, i,t is preferable to control the percentage of the plating powder to the core particles so that it becomes less than 5°/ by mass, and so that the percentage of the metal powder to be used for binding to the core particles becomes less than 3% by mass.
Cooss~
If the percentage aF the plating po~rdex to the care particles becomes more than 5°/ by m~xss, rznd the pezcente.ge o~the metal powder to be used for binding to the core particles becomes more than 3°/ by mass, sznce the quantity of the plating powder having the electrical eanductxvity and the metal powder to be used for bi_n.ding would become too gres.t, the suspension liquid would become nonuniform, and it would became hard to inject the suspension liquid onto the surfaces of the core particles.
~f0037]
Embodiments 1 and 2 Based vn Table 1, embodiments 1 and 2 of this invention, v~rhich use titanium nitride as the plating powder and copper as the metal powder to be used for binding, and comparative examples 1 and 2, are e~rplained below.
[Table 1]

a>

..ra .--i G5 N r~-~

+~ c~
ns .-~ ~',~j ~.'n ao ~~m cd +~ c~.
r-f ~E ~, ~
c~'a ~
~ n U x r o N
~y r, c~
,._, ca o ~ ~ LYj~ OQO ~ ~ N .~jo ~ ,.a G-.
r-i x a'~ a, 0 ro m 0 - o .-~u~ s m x ca d~ ~ ~ ~ o o pd +' c~ ,rs ea ~'co .-ao w E a~ -; .~ c~ ~
~ z c~

x do ''' c~ca cdG7 ~ l"IN

U

H

.~

_~
U P~ 1..~
v1 -O N
m i~ ti V
F~ ~ ~ G~ r~0 ~ .4i ~ ~ ~ ~
~ ~ ~ ~ rr y r-i ~+-i~ ~ Ci~ o ~ w ~ U
~ ~ +' +' a~
C -~ x QY V1 a7 E-~h-. N ~~G7 O
~ Q1p~.,' R ~ ~ ~ ~ ~ _r~
i-i C i-~Q
G7 ~ +~ C4 ~ Z.-rU .r-i P N N rf v1 N N CO
i~+~ +-~ d Cs..~ +~ ca V b O 4 ~ ~ a~i C,aU U ~ ~ E1~ C.a!~
~
~
Lz C~
4~1 ~
E~
r~

[0038]
rn embodiment 1, preliminarily the suspension. liquid is prepared as foilows~ 70 g of powder of titanium nitride having an averF~ge diameter of 7 ~ m is added and mixed with 320 g of r~ PVA solution having a 3%
concentration by mass so that; the final percentage of the powder of the tita~.zum nitride to 1.6 ~.g of the core particles becomes 4.4% by mass.
'Then, 30 g of powder of copper having an arrerage diameter of 10 ,u m as the metal powder to be used for binding (binder) is added and mixed with the PYA solutioz~ so that the final percentage of the powdex of the copper to the core particles becomes 1.9% by m.ae$.
Next, 1.6 ~g of the core particles made from a hard metal shay and having an average diameter of 100 ,u m is put in a coating machine, and the suspension liquid is inyected onto the surfaces of the core particles from a nozzle having a diameter of 0.7 mm with an injection. pxesswe of 0.15 MPs and a flow rate of 1.7 g/min. while the core particles are being heated to 59 °C and are being agitated by centrifugal ~.uidization at 180 rev.lmin.
Consequently, the core particles coated with the powder a~ the titanium nitride and the powder of the copper an the surfaces of them are formed.
(0039]
The core particles are put i.n a furnace that is filled ~xrith nitrogen gas, and then the core particles in the furnace axe heated to 1100 °C
fox oz~e hour. Consequezxtly, all the P'~A is removed, and the solid plating materials, which have cowed layers that are not oxidized and that include the powder of the titanium nitride unifoxz~aly dispersed in the layers by melting the powder of the copper, can be z~a,s.nufactured.
[0040]
''r'he reason that at the final hes,t treatment the furnace is felled with nitrogen gas, and the temperature of the furnace is raised to lloo °C
(heating period is one hour), is as follows ~.'hese conditions are determined based oz~. the relationships stated in claim $ and the facts that the starting temperature of the oxidization of the plating powder (the titanium nitride) is 550---560 °C, axed 'Lhe melting texxiperaturc of the metal powder to be used J.1.

for bindiz~g (the copper) is 1,083 °C.
[0041 Next, 800 g of the solid plating materials manufactured as in embodiment 1 stated above is put in an apparatus for air-blasting. Then, a test piece vuith a diameter of 30 mm axed 4 mm thick and made from stainless steel. ~US316 is fixed iz~ the appar atus. Then the solid plating materials are injected on the entire surface of the test piece under the followi,z,~g conditioz~s: the distance between the test piece and the nozzle:

mm~ the angle between the center line of the nozzle and the surf~xce of the test piece: 90 degrees, the pressure of the injection: 0.3 MPas period of tl~e injection: I8 seconds.
(004:21 Thus, a coated ~Lm of titanium nitride, which is not oxidized, can be fozmed on the surface of the test piece.
[0043 By measuring the contact resistance betv~reen the surface of the test piece and the carbon probe, it was found that the resistance is 3.$ m SZ ~ em2 , and thus is very l.ow. The contact resistance between the carbon probe and the surface of the stainless steel before forming the coated film by' blasting the solid plati.xig materials of this iu.Vention is 500-600 m ~ ~ cm2 .
[00447 A durability test to evaluate the durability of the ct~ated layers of the solid plating materials manufactured as in embodiment 1 was conducted by moans of using tb.e apparatus for air-blasting o.nd a target sample made from steel SS400, and repeatedly blasting the solid plating materials cute the target sample. Coxxsequently, it was found that the solid pl,s.ting materials have excellent durability. Namely, the number of times that the solid plating materials could be used e.gain, which is defined as the number of blasts until 50°Jo of the plated layers are broken away, is $0.
Coo4sl In embodiment ~, the solid plating materials are manufactured by the s~xme method as in embodiment 1, except that when the suspension liquid is injected, the core particles are heated until the temperature reaches 79 °C. The result o~ measuring the contact resistaxxc~ between the coated surface of the test piece and the cs.xbon probe almost equ,0.ls the result of embodiment 1. This indicates that the coated surface has excellent contact resistance. Further, in the durability test, the number of times that the solid plating materials can be reused, which is defined as a number of blasts until 50°/ of the plating layers are broken away, cannot reach $0_ The number of times that the solid plating materials of embodiment 2 can be reused is 50. Zt was found that the solid plating materials still have good durabilrt~r bIence, the method for measuring the contact resistance and the method for evaluating the durability are the same as those of embodiment I.

Next, comparative examples 1 and 2 are explained. In comparative example 1, the solid plating material is manufactured without usxx~g any metal pov~rder to be used for binding. In the manufacturiz~g process, when the suspension liquid is injected r~nto the surfaces of the care particles, the core particles are heated to 80 ~C, which is near the temperature of embodiment 2. rn comparative example 2, the solid plating materials are manufactured ~srii:hout using any metal powder to be used fc~r ban.ding_ Further, in the manufacturing process of comparative example 2, when the suspension liquid is injected onto the surfaces of the core particles, the core particles are heated to 5~J °C, as in embodiment 1. Table 1 shows the contact resistance between the coated surface of the test piece and the carbax~ pzobe. That table indiaa~tes the electrical conductivity of the coated leyers, rind the results of the durability tests of the coated ls,yers o~tl~e sol,i.d plating xa,aterials of comparative examples 1 and 2. 1-fence, the method for measuring the contact resistance and the method for evaluating the durability ors also the same as those of embodiments 1 and 2.
foo4~1 For the results showing the aantact resistance between the coated surface of the test piece and the csrbon probe, since the difference between the contact resistance of comparative examples 1 and 2 s,r~d ths.t of embodiment X is W'ithi.n about 10%, it was found that the test piece has excellent electzieal conductivity The mason for this is that electrically oonductiwe coated layers that are not oxidized are formed because the plating powder (the titanium nitride) used in comparative examples 1. and 2 is the same as that of embodiment 1, and because at the final heat treatx~n,ez~t the ~uznace is :~.ll,ed wi~;b~, nitxogen gas, axxd tk~e temperature of the furnace i.s Faxsed to 1X00 ~, as in embodiment 1.
x3 (oo4sl However, from the results o~ the teat to evaluate the durability of the coated layers formed on the suxf~xces of. the core particles, it is Been that the results of comparative exampJ.es X and 2 are significantly inferior to those of embodiments 1 and 2, This is because in comparative examples 1 and 2, the coated layers bound to the surfaces of the particles are brittle, because n.o xxietal powder to be used for binding is included. Thus, the xeeult of the test to evaluate the durability of the coated layers shows no advantage.
[0049]
Embodiment 3 Table 2 shows embodiment 3 of this invention, Xn embodiment 3, titanium. nitride is used as the plating powder, and tin is used as the metal pov~der to be used ~ox binding.
[Table 2]
Items Emt~odimerii:

A Care Particle Lard metal alloy Content of Organic Binder (~ mass) 3 by Content of Titanium Nitridef~ mass) 4.2 by Content of Powder of Tin (% mass) 1.8 by Temperature of the Core when 64 Particles injecting __ Suspension l.xquid (9C) Atmosphere in the Furnace Air Temperature in the furnace (~C) 250 Number of Reuses of the 65 Solid Plating Material Contact Resistance (mSa cm2) 7. 5 Durability of the Coating (food Layer 1~1 [0050]
In embodiment 3, preliminarily the suspension liquid as prepared as follows 67 g of powder of titanium z~itride having an avez~s.ge diametor of 7 a m is added ,end mi..Yed with 320 g of a PV'A solution having a 3%
concentration by mass so that the final percentage of the powder of titanium nitzade to 1.6 Kg of the core particles becomes 4.2% by mass. Then, 29 g of pov~rder of tin having an avez~s.go diameter of 10 a m as a metal powder to be used fox binding (binder) is added arid mixed with i;he PVA solution so that the final percentage of the powder of the tin to the core particles becomes L8% by mass.
Next, 1.6 Kg of the core particles made from a hard metal alloy end having an average diameter o~ i00 a m is put in a coating machine, and the suspension liquid ie injected onto the surfaces of the core particles from a nozzle having a diameter of 0.7 mm with an injection pressure of 0.15 MPa and a flow rate of 1.7 glmin. v~rhile the core particles axe being heated to 64 9C and are agitated by centzifugal fl.uidization at X30 rev,lmin.
Consequently, core particles coated with the po~xrder of the titaz~.ium nitride and the powder of the tin on the surfaces of there are formed.
[0051]
The care particles are put in a furnace that is filled with air. Then the core particles in the furnace are la.eated to 250 °C far two booze.
Consequently, all the PVA is rena.owed. Thus solid plating materials that have coated layers that are not oxidized az~d that include powder of titanium nitride unifozmly dispersed in. the layer by melting the powder of the tin can be manufactured.
Coo52]
'Z'he reason that at the final heat treatment the furnace ~s filled with axr, and the temperature o~ the furnace is raised to 250 °C (heating period is two IZOUrs), is as follows: These con.ditioz~s are determined based on the relationships as in claim 8 and the facts that the starting temperature of the oxidization of the plating powder (the titanium nitride) is 550-560 °rC, az~d the melting temperature of the metal powder to be used for binding (the tiz~) is 232 9C.
[00581 Next, S00 g of the solid plating materials manufactured as ice, embodiment S stated above is put in an apparatus for air-blasting. Then, under the same conditions r~s in embodiment 1, such as the i:est piece used to form a coated film, the distance between the tort piece and the nozzle, the aza,gle between the center line of the nozzle and the surface of the test piece, the pressure of the injection, and the period of the injection, the solid plating materials are injected onto the entire surface of the test piece.
Consequently, a coated filxx~. of titanium nitride, which is not oxidized, can be formed on the sitxrface of the test piece.
[0054]
By measuring the contact resistance betv~reen the surface of the test piece and the carbon probe, it ws.c~ found that the resistance is 7.5 m Sl cn~~ , and thus is ver, y low.
(0055]
A durability test to evaluate the durability of the coated layers of the solid plating materials manufactured as in embodiment 3 was conducted by means of using the apparatus for ai,z~-bl$sting and a target sample made from steel SS400, and repeatedly blasting the solid plating ~nn.aterials onto the target sample. Consequently, xt was found that the solid plating materials have good durability. Namely, the number of times that the solid plating materials cr~n be reused, which is defined as a number of blasts until 50°/ of the plating layers is broken away, was 65.
L0056~
Embodiment 4 Table ~ shows embodiment 4 of this inventioz~. In embodiment 4, vanadium carbide is used as the plating powder, and copper is used as the metal powder to be used for binding_ ETable 3l Ttems Embodiment A Core Particle Hard metal alloy Content of Organic binder (3o by mass)3 Content of Vanadium Carbide (% by mass) 4.4 Content of Powder o~ Copper (96 by mass)1.9 Temperature of the Core Particleswhen Tn~ecting64 Suspension Liquid (C) Atmosphere in the Furnace Nitrogen Gas Temperature in the rurpace (C) 1,100 Number of Reuses of the Solid 92 Plating Material Contact Resistance (m~ emz) 3, 3 Durability of the Coating Excellent Layers toos~~
In embodiment ~, preliminarily the s~xspez~sion liduid is prepared as follows: 70 g of powdez~ of vanadium. carbide having an average diameter of 1.8 a m is added and mixed with 320 g of a PVA solution having a 3%
concentration by xn.ass so that the final percentage of the powder of the vanadium carbide to 1.6 Kg of i;he pore particles becomes 4.4a/ by mass.
Then, 30 g of powder of copper having an average diameter of 10 a m, used as a metal powder to be used far binding (binder), is added and mixed with the T~'VA solution so that the final percentage of the powder of the copper to the core particles becomes 1.9°f° by mass.
Next, 1,6 Kg of the core particles made from ~: hard metal alloy and having an. average diameter of X00 ~u m was put in a coating machine, and the suspension liquid was injected onto the surfaces of the core particles from a nozzle having a diam,ater of 0.'7 znm with an injection. pressure of 0.15 IVIPa and a flow rate of 1.7 glznin. while the core particles ~uvere heated to 64 °C and were agitated by centrifugal fluidization at 130 rev/min.
Consequently, core particles coated with the powder of the vaz~adi.uxx~
carbide and the powder of the copper on the surfaces of them wore formed.
[0058]
The coxe particles were put in e. furnace that was filled with nitrogen gs.s_ Then the core particles in the furnrxce were heated to 1100 °C for one hour. Consequently, all the PVA was removed. Thus, solid plating materials that have coated layers that are not oxidized and i;hat include pavv~der of vanadium carbide uniformly dispersed in the layers by melting the powder of the copper, can be manufactured.
[0059]
The reason that at the final heat treatment the furnace is filled with nitrogen gas and the temperature of the fuznace is raised to 1100 °C (a heating period of one hour) is as follows: These conditions are determined based on the relationships stated in claim $ and the facts that the starting teznpexatuxe of the oytidization of the plating powder (the vanadium carbide ) is 440-460 'jC, and the melting temperature of the metal powder to be used for binding (the copper) is X,0$3 9C.
[0060]
Next, $00 g of the sol.xd plating meterials manufactured as in embodiment 4 stated above was put iz~ az~ apparatus foz aiz-bl~asting_ Then, under the same conditions as in embodiment 1, such as the test piece to ~orz~, a coated film, i;he distance between the test piece and the nozzle, tl~e angle betrnreen the center line of the nozzle and the surface of the test piece, the pressure of the injection, and the pexzod fox izajecti.oxx, the solzd plating materials were injected onto the en'~ire surface o~ the test piece.
Consequently, a coated film of vanadium carbide, rasrhich is not oxidized, can be formed on the surface of the test piece.
[0061]
Py measuring the contact resistance between the surface o~ the test piece and the carbon probe, it was found that the resistance is 3.3 m SZ ~ cm2 , and thus is very low.
[OOfi2]
A durability test to evaluate the durability of the coated layers of the solid plating materials manufactured as iz~ exxxbodi,zn~ent 4 was conducted by means of using the apparatus far air-blasting and a target sample made 1$

from steel SS400, and repeatedly blasting the solid plating materi~xJ,s onto the target sample. Consequently, it was found that the solid plating materials have excellez~,t durability Namely, the number of times ths~t the solid plating materials can be reused, which is defined as the number o~
blasts until 50°/a of the pla,ti.z~,g layers is broken away, zs 92.
[0063]
Etnbodimez~t 5 'fable 4 shows ezxzbodiment 5 of this invention. In embodiment 5, vanadium carbide is used as the dating powder, and tin as used as the metal powder tp be used for binding.
[Table 4]
Items Embodiment A Core Particle Hard metal alloy Content of Organic Binder (96 by mass) 3 Content of Vanadium Carbide (96 by mass) 4. 2 Content of Powder of Tin (96 by mass) x, 8 Temperature of the Core ParticJ,eswhen Injecting64 Suspension Liquid (C) Atmosphere in the Furnace Air Temperature in the Furnace (C) 250 Hum6ex of Reuses of the Solid 68 Plating Material Contact Resistance (mSd ~ cm2) 8. 4 purability of the Coating Govd Layers [OOG4]
In embodiment 5, preliminarily the suspension liquid is pxepared as follows: 67 g of powder of vanadium, carbide having an average diameter of 1.8 ,u m is added and mixed with 320 g of a PVA solution having a 3%
coneentxation by mass so that the ~n.al percentage of powder of the vanadium carbide to 1.6 Kg of the core pazti,cles becomes ~:.2% by mass.
Then, 29 g of powder of tin having an average diameter of 10 ~c m, as a metal powder La be used for binding (binder), was added and mixed with the PVA solution. Thus, the final percentage of the pawder of the tin to the core particles became 1.$% by mass.
Next, L0 Kg of core ps.ri;icles made from a hard metal alloy and having an average diameter of 100 a m was put in a coating machine.
Then the suspension liquid was injected onto the surfaces of the core particles from a nozzle having a diameter of p.7 mm with an injection pressure of 0.15 MPa. and a flow rate of 1.7 g/min. whiffs the core particles were heated to F4 °G and were agitated by centrifugal fluidization at rev.lm.in. Thus, core particles coated with the powder of vanadium carbide and the powder of tin on the surfaces of thorn were formed.
[0065) The core particles were put iii a furnace that was filled with air.
Then the core particles in the furnace were heated tc~ 250 °C: far three hours.
Consequez~tly, all the PVA was removed. Thus, solid pls.ting materials that have coated layers with a uniform distribution of powder of vanadzum carbide, which is caused by melting the powder of the tin and that is not oxidized, ce.n be ~nanufactuzed.
[0066]
The reason that at the final heat treatzz~ent the furnace was filled with air and the tempersture of the furnace was raised to 250 °G
(heating period was three hours), is as follows: These conditions were determined based on the relationships stated in claim $ and the facts that the starting temperature of the oxidisation of the plating powder (the vanadium carbide) was 440---450 °G, and the melting temperai;ure of the metal powder to be used for binding (the tin) was 2S2 9C.
[006'7]
Next, $00 g of the solzd plating material manufactured as in.
embodiment 5 abo'~e was put in an apparatus for air-blasting. Then, under the same conditions as in embodiment 1, such as a test piece to form a coated film, the distance between the test piece and the nozzle, the angle between the center line of the nozzle and the surface of the test piece, the pressure of the injection, and the period for injection, the solid plsting materis.ls were injected auto the entire surface of the test piece.

Consequently, a coated film of vanadium carbide thet i,$ raot oxidized was able to be formed on the surface of the test piece.
L0068]
By measuring the contact resistance between the sur~ace of the test piece and carbon probe, it was found that the resistance is 8.4 m S~ ~ cm2, and is thus very low.
f00egl A durability test to evaluate the durability of the coated layers of the solid plating materials manufactu~.~ed as in embodiment 5 was conducted by means of using an apparatus for air-blasting and a target eaxnple made from steel SS400, and repeatedly blasting the solid platzn~ materials at the target sample. Consequently, it vVas found that solid plating materials have good durability. Namely, the number of times that the solid plating m~xterials egn be reused, which is defined as a number of blasts until b0% o~
the plating layers is broken away, is 68.

Claims

1. A method for manufacturing solid plating materials, comprising:
a step for preparing a suspension liquid by mixing plating powder having electrical conductivity and a metal powder to be used for binding with a coating fluid which includes an organic binder, a step for forming layers on surfaces of core particles, which layers include the plating powder and the metal powder to be used for binding, wherein the plating powder and the metal powder are bound to the surfaces of the care particles by the organic binder, by means of injecting the suspension liquid onto the surfaces of the core particles while the core particles are being agitated by centrifugal fluidization, and a step for removing the organic binder and forming the coated layers bound to the surfaces by melting the metal powder, which layers include the plating powder, by means of heating the core particles until the temperature is above the melting temperature of the metal powder.

2. The method of claim 1, wherein in the step for forming the layers the suspension liquid is injected onto the surfaces of the core particles while the core particles are being further heated to 30-70°C.

3. The method of either of claims 1 and 2, wherein in the step for forming the layers the suspension liquid is injected onto the surfaces of the core particles with a flow rate of 0.5-2 g/min.

4. The method of any of claims 1-3, wherein the coating fluid is comprised of water or a mixture of water and alcohol that includes less than 4% by mass of the organic binder.

5. The method of any of claims 1-4, wherein the plating powder consists of powder of an electrically conductive ceramic having an average diameter of less than 20 µm.

6. The method of any of claims 1-5, wherein the melting temperature of the metal powder to be used for binding is lower than that of the core particles, and wherein the average diameter o~ the particles of the metal powder is less than 20 µm.

7. The method of any of claims 1-6, wherein the average diameter of the core particles is less than 2 mm, and wherein the core particles are made from any of a hard metal alloy, steel, a nonferrous metal, or a nonmetallic inorganic substance.

8. The method of any of claims 1-7, wherein the core particles are heated based on the following conditions:
when the melting temperature of the metal powder to be used for binding is 350°C or above or 50°C or more below the starting temperature for the oxidization of the plating powder, the core particles are heat-treated in a non-oxidative atmosphere, and when the melting temperature of the metal powder to be used for binding is less than 350°C or is less than 50°C below the starting temperature of the oxidization of the plating powder, the core particles are heat-treated in air.

9. The method of any of claims 1-8, wherein the percentage of the plating powder to the core particles is less than 5% by mass, and wherein the percentage of the metal powder to be used for binding the plating powder to the core particles is less than 3% by mass.

10. A solid plating material which is manufactured by the method of any of claims 1-9.